Many parts of the world remain littered with unexploded ordnance, posing a danger to civilians and in many instances impeding use of cropland. In addition, stockpiles of unused but now obsolete and in some cases, dangerous artillery and other large ordnance shells need to be disposed of.
Although in some cases such shells can be disarmed, this is often either dangerous, too time consuming and expensive to provide a practical solution.
It is known to destroy ordnance high explosive and chemical shells by subjecting them to a controlled explosion. See following document for a description of this process;
Demonstration/Validation of the TC-25 Donovan Blast Chamber, Porton Down, UK, Final Demonstration Test Report, April-September 2003
Authors: Timothy A. Blades; Raymond DiBerardo; Gregory Misko; Niel McFarlene; EDGEWOOD CHEMICAL BIOLOGICAL CENTER ABERDEEN PROVING GROUND MD http://www.stormingmedia.us/73/7325/A732524.html U.S. Pat. No. 6,647,851 to Donovan (published November 2003) describes the principles of wrapping a munition with an externally applied explosive material for the purpose of destroying the munition. The disclosure of U.S. Pat. No. 6,647,851 is incorporated herein by cross reference. FIG. 4 of that patent is reproduced in FIG. 1 of this specification as acknowledged prior art.
Typical methods as described in the documents quoted above are to enclose the shell in a quantity of malleable elastomeric or plastic explosive with a high detonation velocity and high detonation pressure, or to array a system of linear and conical shaped charges around the contained shell. In the case of detonating of the enclosing explosive, this detonation pulverizes the shell casing and either detonates the explosive material within or, in the case of a non explosive shell filling, for example sulphur or nitrogen mustard agent (well known WW 1 and WW2 chemical warfare agents), disperses and partially decomposes these agents, and similarly other chemical warfare agents such as lewisite and phosgene. It is to be noted that the above described procedure and effect is only conducted, in the case of ordnance shell (and other ordnance ammunition such as mortar shells, rocket warheads and bombs) containing chemical agent, in a specially constructed blast chamber. Such chambers are provided with suitable equipment designed to pyrolise, chemically react, and filter any chemical agent remnants so as to render these remnants harmless.
In addition, a shaped charge system for the destruction of chemical munitions is described by the Board on Army Science and Technology at
http://www.nap.edu/openbook.php?record id=10646&page=56.
In this system, a munition to be destroyed is placed in a blast chamber and exposed to detonation of a combination of linear and conical shaped charges. The linear charge comprises a preformed length of RDX-based, copper-sheathed LSC (linear shaped charge) specific to the shape and length of the munition, and is designed to make a complete cut in the munition. Two conical shaped charges (CSC) are used to break open the burster charge canister in the munition and detonate the explosives.
Another method known in the industry is to surround the ordnance shell with a watergel or emulsion explosive, within a blast chamber, and detonate the said explosive. A relatively greater mass of the watergel or emulsion explosive is used for this task, compared to wrapping the shell with elastomeric sheet or plastic explosive. This is because the detonation pressure of the watergel or emulsion explosive is substantially lower than the detonation pressure and detonation velocity of the above described elastomeric or plastic explosive.
These methods of disposal while effective, are inefficient or complicated as well as being relatively time consuming. As well, explosive sheet is an expensive explosive in comparison to the above described watergel or emulsion explosives, and also compared to the present invention's preferred explosives, Hexolite or Pentolite or TNT. The United States is most probably the largest manufacturer of sheet elastomeric and malleable Plastic explosive although there are similar products made in Europe, Russia China and elsewhere—although, in each case, the product is relatively expensive compared to the cheap and abundant cast explosives, Hexolite and Pentolite or TNT, all of which are in common use for both the defence and mining industries in many countries. It should be noted that, especially in the Case of Pentolite and Hexolite, that their detonation velocities and pressures are more than adequate for the intended use, far superior to watergel or emulsion explosives, and slightly less effective than elastomeric or malleable explosives in terms of delivering shock energy to ordnance items as described. TNT is also more effective than emulsion or watergel explosives, and slightly less effective than either Pentolite or Hexolite, although sufficiently effective, and cheap, to be utilised in the intended role. For preference, Hexolite will be the most effective explosive for the intended purpose, although all three of these cast explosives will perform more than adequately.
Exemplary velocities of detonation of the explosives disclosed above are respectively as follows:
P2000 sheet (elastomeric) explosive—8200 meters/sec
C4 Plastic Explosive—8200 m/sec
Hexolite (60% RDX, 40% TNT)—7900 meters/sec
Pentolite (50% P.E.T.N, 50% TNT)—7400 meters/sec
T.N.T—6900 meters/sec
A.N (ammonium nitrate) Emulsion—5200 meters/sec
A.N Watergel—4200 m/sec
There also tend to be export restrictions on, for example, Primasheet 2000 and C4 plastic explosive, specialised elastomeric, malleable explosives that could also be suitable for the disposal of munitions task because the US government regards RDX containing elastomeric and plastic explosives as a controlled export category product, as it is primarily for military use.
These products contain high percentages of RDX explosive (cyclo trimethylene trinitramine)
It is an object of the present invention to address or at least ameliorate some of the above disadvantages.
Notes
1. The term “comprising” (and grammatical variations thereof) is used in this specification in the inclusive sense of “having” or “including”, and not in the exclusive sense of “consisting only of”.
2. The above discussion of the prior art in the Background of the invention, is not an admission that any information discussed therein is citable prior art or part of the common general knowledge of persons skilled in the art in any country.